1. Field of the Invention
This invention is generally directed to devices for securing electrical connectors, such as male and female plugs associated with power conductors and power tools and the like, in assembled or united engagement so that electrical power through the plugs is not interrupted by the plugs being accidently separated. More specifically, the present invention is directed to a coupling restraint assembly which includes a pair of generally identically configured U-shaped flexible mounting straps which are secured relative to each of the male and female connectors in opposing relationship with respect to one another using integrally formed locking tabs which are extendable through openings provided in each strap. The mounting straps are constructed so as to be used interchangeably on different types and sizes of power cords and electrical connectors. In a preferred embodiment, a pair of self-binding restraint straps are secured to two legs of one of the generally U-shaped mounting straps and are selectively extendable through openings in opposing leg portions of the adjacent mounting strap. The restraint straps are secured upon themselves by the use of fastening elements of a hook and loop material such as VELCRO.
2. History of the Related Art
Most power tools and heavy duty appliances include a relatively short power cord having a male electrical connector at the end thereof. For all practical purposes, and in particular with power tools such as saws, blowers, hedge trimmers, mowers, drills, and the like, the power cords are only provided as a means by which extension cords can be connected to provide power to the tools. That is, the tools are generally designed for use in an area remote from a power source, such as an electrical socket, and therefore it is almost always necessary that an extension cord be utilized to connect the short power cord associated with the tool or appliance with an electrical socket.
Unfortunately, when utilizing extension cords to connect power equipment to sources of electrical supply, the only locking arrangement provided between the male and female connectors is the friction fit of the prongs of the male connector within the female electrical sockets. Any force exerted along the length of the power cord generally results in the electrical connectors being separated and, in some instances, this can result in very hazardous situations wherein current arcing between the male and female electrical connectors can create sparks or cause damage to the electrical connectors. In some instances, where power tools are designed to be utilized in environments where they are subject to moisture, a loose connection between the power plugs can result in a shorting of electrical energy which can result in electrical shock and potential danger to the individual utilizing the appliance or tool.
To overcome the problems associated with retaining electrical connectors in assembled relationship, there have been many securing devices developed for assuring the mechanical connection of the male and female plugs with the contacts fully seated with respect to one another. Prior to the provision of such supplemental securing devices many individuals simply tied the ends of electrical cords carrying the male and female plugs together and thereafter united the plugs. Such connections are very hazardous and can damage the electrical conductors within the power cords and further do not result in substantially tight and flush seatings of the male connectors within the sockets of the female plugs thus allowing portions of the electrical contacts to be exposed.
Many supplemental coupling adaptors or restraints require modifications to power cords or electrical plugs. By way of example, in U.S. Pat. No. 4,440,465, to Elliott, several embodiments of securing devices are disclosed. In one embodiment, studs are integrally molded with a female connector. A separate strap is mounted to the power cord carrying the male electrical plug with the strap therefrom having a plurality of openings which may be penetrated by the studs of the female connector. Unfortunately, the openings in the strap mounted to the male plug must be spaced relative to one another. Therefore, the only adjustment available is not continuous between the male and female plugs when they are connected and thus, unless the connection is absolutely perfectly aligned between the studs and the openings, the restraints will be generally loosely fitted relative to the electrical connectors. Further, with these types of devices, it is necessary to integrally form the female plug with the required studs. Such a structure is impractical for use with most power tools which are not modified in order to receive a supplemental restraint or securing device.
A similar type of arrangement is disclosed in U.S. Pat. No. 4,514,026 to Herbert, where in one embodiment a plurality of studs are provided on the female plug. However, with this connector there is no separate strap attached directly to the male connector. The strap extends from the female connector and is wrapped around the male connector and thereafter returned to interfit with the studs which are formed on the female connector. Again, the spacing between the openings and the locking studs is not variable and the strength of the assembly will be determined by the degree in which it is possible to wrap the integral strap carried by the female plug relative to the male plug. As with the previous connectors discussed above, this type of connector requires that the female plug be originally molded to include the locking or restraint device, which is impractical.
An arrangement similar to the previous two examples is disclosed in U.S. Pat. No. 4,596,430 to Olson. In this patent, a separate strap member having opposing end portions is wrapped about one of the power cords leading to either the male or female power plug. A pair of studs extend from the outer end portions of the strap member and are selectively engageable within contoured openings which are formed in, or molded in, the sidewalls of the plugs of the mating male or female connector. This device requires that the openings be provided in the opposing power plugs so as to receive the tabs or studs carried at the end of the flexible strap. Such a device either requires that the plugs be integrally formed to incorporate the openings for receiving the studs or that some mechanical change be made to the plugs. Mechanically altering the plug housings by drilling holes in the sides would be extremely dangerous and could potentially lead to situations wherein conductors within the plugs would be exposed by such tampering with the structural integrity of the plugs.
The aforementioned patent to Elliott discloses an alternate embodiment wherein there is no requirement to specifically modify either the male or female plug or connector. In the reference, a pair of U-shaped mounting brackets are designed to be frictionally engaged about the power cord at the base of both the male and female electrical plugs. One of the straps extending from the mounting brackets is provided with outwardly projecting studs while another strap is provided with a series of openings which are spaced equally to the spacing of the studs. Once the straps are placed in opposing relationship, the straps are united to one another by passing the studs through the openings of the opposing strap members. As previously discussed, the effective connection or joint between the male and female plug is dictated by the spacing between the studs and the openings in the flexible strap members. Further, such devices are designed to be utilized only with power cords having a circular cross section and are therefore not appropriately designed for use with power cords having other cross-sectional configurations. Also, because of the friction engagement of each of the base portions of the straps with the power cords, if any stress is placed to separate the straps, the clips on the base portions may be easily removed from the power cords thereby defeating the overall securing nature of the straps.
In the patent to Herbert, another embodiment is shown wherein a single strap is provided having studs at one end and openings at the other. The same alignment problem is found wherein the potential for a loosely fitted engagement of the strap relative to the electrical connectors is possible because of the relative alignment between the studs on one end of the strap and the openings on the other. Further, utilizing a single strap to wrap about opposing connectors does not provide positive locking engagement of the strap and only frictionally binds the connectors together in a configuration which can be overcome if any twisting is developed between the plugs.
Another type of coupling device which requires modification or permanent placement of the coupling members to the opposing plug members is disclosed in U.S. Pat. No. 4,917,626 to Barton. In this patent, the female plug is modified by applying two strips of looped fabric material such as VELCRO which strips are adhesively secured on either side of the female connector. A pair of elongated straps are likewise adhesively secured on opposite sides of the male plug with the straps including hook elements utilized in a VELCRO fastening system. When the male connector is united with the female connector the hooked straps are pulled over opposing looped material and thereafter engaged to retain the connectors in fixed relationship with respect to one another. Such a permanent modification to existing plug elements is generally impractical. It would be preferred to provide securing devices which may be utilized interchangeably between various types of power cords and extension cords without requiring permanent attachment of the coupling elements to such power cords or connectors. In addition, the strength established by simply mating a hook and loop material as taught by the reference would not be sufficient to overcome any significant amount of stress placed along the power cords.
Another type of securing device for power plugs is disclosed in U.S. Pat. No. 4,690,476 to Morgenrath. This patent discloses connecting devices which incorporate VELCRO fasteners in a manner which increases the strength and holding capacity of the engaging loop and hook fabric material. The securing device includes a pair of opposing strap members which are secured about electrical conductors by utilizing a pair of wire ties which attach the end portion of the straps at the base of each of the male and female plugs. One of the straps includes VELCRO materials which are spaced relative to one another while the other of the straps includes ring openings through which the VELCRO members of the opposing strap may be selectively inserted. Once inserted through the opposing straps the VELCRO fasteners are folded over on themselves thereby providing a locking arrangement which is generally continuously adjustable to insure a tight engagement of the power plugs with respect to one another. As the VELCRO material is folded through the loops a great deal of the stress which would be imparted between the two opposing straps is offset by the straps themselves and transmitted to the power cord prior to the hook and loop fastening materials having to counter such stress. Therefore, a distinctive advantage in holding capacity is achieved over structures such as that disclosed in U.S. Pat. No. 4,917,626 to Barton.
Unfortunately, the securing devices disclosed in the reference to Morgenrath require that the base of the unit to be tied to cylindrical power cords and secured thereto utilizing separate wire ties. This assembly is therefore somewhat complex and the wire ties are not easily removable to permit the strap members to be changed or moved from one power cord to another without difficulty. Further, the opposing strap members are separately constructed and therefore each joint must require that the proper strap members be available to create the joint.